Effects of Di(2-ethylhexyl)phthalate on Bone Metabolism in Ovariectomized Mice

BACKGROUND: The molecular pathways of how endocrine disruptors affect bone mineral density (BMD) and bone remodeling are still unclear. The purpose of this experimental study is to determine the effects of di(2-ethylhexyl)phthalate (DEHP) on bone metabolism in ovariectomized mice. METHODS: Twenty-six-month-old female CD-1 mice were divided into 4 groups: control, low-dose DEHP, high-dose DEHP, and estrogen groups (n=5, each group). All mice were subjected to ovariectomy for the induction of artificial menopause and then exposed to corn oil, DEHP, and estrogen for 2 months. Micro-computed tomography (Micro-CT) of the bone and analysis of blood samples for bone markers were performed to observe the changes in bone metabolism. RESULTS: Osteocalcin level was decreased in the control, low-dose and high-dose DEHP group, the reduction width was greater in the high-dose DEHP group (−0.219 ng/mL) than control group (−0.077 ng/mL, P<0.05). C-terminal telopeptide of type I collagen level was increased in the control, low-dose and high-dose DEHP group, the increase range of low-dose DEHP group (0.329 ng/mL) showed greater than control group (0.093 ng/mL, P<0.05). Micro-CT analysis revealed that the BMD was significantly lower in the high-dose DEHP group (19.8×10⁻² g/cm³) than control group (27.2×10⁻² g/cm³, P<0.05). The structure model index was significantly higher in the high-dose DEHP group (2.737) than low-dose DEHP group (2.648) and estrogen group (2.63, P<0.05). It means the progression of osteoporosis in the high-dose DEHP group. CONCLUSIONS: These results confirm the negative effects of DEHP on bone health in ovariectomized mice. Further continuous studies on genetic pathways and other endocrine disruptors will be necessary to validate these findings.

Effects of combined treatment with diethylhexyl phthalate and bisphenol A on hepatic injury and oxidative stress in rats liver / 中国职业医学

OBJECTIVE: To observe the hepatic injury induced by combined exposure to diethylhexyl phthalate( DEHP) and bisphenol A( BPA) in rats and explore the mechanism of oxidative stress. METHODS: Thirty-two specific pathogen free healthy male SD rats were randomly divided into control group,DEHP(750 mg/kg body weight) group,BPA(100 mg/kg body weight) group and combined exposure group,with 8 rats in each group. The rats were gavaged once per day,7 days per week,for 6 weeks. The changes of liver organ coefficient and histopathology were observed. The activities of superoxide dismutase( SOD), glutathione peroxidase( GSH-Px) and the levels of hydrogen peroxide( H2 O2),malondialdehyde( MDA) were detected by spectrophotometry. The relative mRNA expression of antioxidant gene nuclear factor erythroid-2 related factor 2( Nrf2),heme oxygenase-1( HO-1),glutamate cysteine ligase catalytic subunit( Gclc),thioredoxin reductase( Txnrd),superoxide dismutase 3( Sod3) and glutathione peroxidase 1( Gpx1) in liver tissue were examined by real-time fluorescent quantitative polymerase chain reaction. RESULTS: The body weight of DEHP exposure group was lower than that of control group from the beginning of the 2 nd week( P < 0. 05),and the body weight of combined exposure group was lower than control group from the beginning of the 3 rd week( P < 0. 05). The liver mass and organ coefficients in DEHP group and combined exposure group were significantly higher than that of control group( P <0. 05). The results of pathology examination showed that there was necrosis of liver cells in DEHP group,vacuolar degeneration in cytoplasm of BPA group,and severe inflammatory cell infiltration in combined exposure group. The activity of SOD and GSH-Px of each exposure group was reduced( P < 0. 05),the H2 O2 level of each exposure group was increased(P < 0. 05),meanwhile the MDA level in the liver tissue of the BPA group and the combined exposure group increased compared with the control group( P < 0. 05). The relative mRNA expression of Nrf2,HO-1 and Gpx1 in each exposure group were decreased( P < 0. 05),the relative mRNA expression of Gclc,Txnrd and Sod3 in DEHP group and mixed exposure group were decreased compared with the control group( P < 0. 05). The relative mRNA expression of Nrf2,HO-1,Gclc,Txnrd and Sod3 in combined exposure group were decreased compared with the BPA group( P < 0. 05).CONCLUSION: Under the conditions of this study,DEHP and BPA alone or in combination could cause hepatic injury. The combined effect was greater than single effect. The effect of DEHP was greater than that of BPA. The liver injury induced by DEHP and BPA was related to Nrf2 signaling pathway.

Experimental study on DEHP affect the neurodevelopment through interfering with placental thyroid hormones transport / 中华劳动卫生职业病杂志

Objective@#The present study was represented by di-(2-ethylhexyl) phthalate (DEHP), to explore the role of thyroid hormones (THs) disruption in the connection of placenta and neurodevelopmental toxicity.@*Methods@#During fetal mice neural tube closed (pregnancy 9.5 days, E9.5d) to begin synthesis of THs (E15.5 d), all pregnant mice were administered with different concentration of DEHP (0、10、50、200 mg/kg) by gavage once a day(10 mice per group). All pregnant mice were conducted with BrdU administration in E14d by subcutaneous injection. Seven pregnant mice from each group were scarified after anesthesia in E15.5 d, serum and amniotic fluid were collected to determinate the levels of THs(T3, T4, FT3 and FT4) by the automatic biochemical analyzer, detecting fetal mice placental protein expression of monocarboxylate transporter 8 (MCT8), organic anion transporting polypeptide 1C1 (OATP1C1) and deiodinaseⅡ&Ⅲ (DIO2, DIO3) by Western blot. Each group of the remaining three pregnant mices were killed after anesthesia in E18d, take the male fetal brain, BrdU immunohistochemistry was used to detect the proliferation and migration of fetal brain cortical neurons.@*Results@#There was no abnormalities in diet, water intake, body weight and general activity of pregnant mice in each treatment group, and there were no difference in the general physiolo. Results There was no abnormalities in diet, water intake, body weight and general activity of pregnant mice in each treatment group, and there were no difference in the general physiological development status of body weight, brain weight, brain body ratio between the mice of each group. There was no statistically significant differences in serum T3, T4, FT3, FT4 and amniotic fluid FT4 in pregnant mice of each group (P>0.05), Compared with the control group, the FT3 levels in the amniotic fluid of the DEHP 50 and 200 mg/kg groups were significantly decreased(P<0.05). Compared with the control group, the placental MCT8 and DIO2 protein levels of male fetal mice in the DEHP 50 and 200 mg/kg group decreased, and the level of OATP1C1 protein in 200 mg/kg group decreased(P<0.05), and there was no statistically significant difference in DIO3 protein levels among all groups (P>0.05). Compared with the control group, the number of BrdU positive cells in the cerebral cortex of male mice in DEHP 200 mg/kg group decreased, 56.5% was distributed in VZ-SVZ layer, and the percentage of BrdU positive cells in the IZ layer of 50 mg/kg group increased (P<0.05).@*Conclusion@#DEHP 50, 200 mg/kg may affect the proliferation and migration of neural cells in the developing brain, which may be related to its interference with thyroid hormone by placental transport.

Effect of di-(2-ethylhexyl) phthalate on lung morphology of newborn rats / 中华围产医学杂志

Objective To investigate the effect of di-(2-ethylhexyl) phthalate (DEHP) on the postnatal lung development in newborn rats.Methods A total of 60 newborn Sprague-Dawley rats (weighing 5.0-8.0 g) in five age groups were studied in the first experiment.The rats were divided based on the different postnatal ages:postnatal day (PND)I,PND4,PND7 and PND14.A total of 45 newborn Sprague-Dawley rats (weighing 5.0-8.0 g) were randomly divided into three groups according to the dosage of DEHP administered in the second experiment.The newborn rats were administered DEHP through intraperitoneal injection at 10 (low-dose subgroup),100 (medium-dose subgroup) or 750 (high-dose subgroup) mg/kg daily from PND1 to PND13.The rats were sacrificed on PND14.Pups were sacrificed with lethal dose injection of pentobarbital sodium.The lung was removed.The right middle lobes were used for analysis.The tissue was processed for histology and lung sections were stained with HE for light microscopic (LM) morphometric measurement.The analysis was performed by means of a digital image analysis system,including pulmonary interstitial area ratio (IAR) and total length density of all segments.One-way ANOVA,LSD and Dunnet T3 methods were used for statistical analysis.Results In the normal controls,IAR decreased significantly by (31.97±5.03) ％,(30.05±3.57)％,(25.33± 1.83)％ and(22.01 ±2.19)％,respectively,from PND1 to PND14 (P＜0.05 or P＜0.01).IAR in medium-and high-dose subgroups increased significantly by (24.11 ±2.78)％ and (26.53± 3.42)％,respectively on PND 14.The total length density of all segments in unit area lung volume increased significantly by 0.047 8±0.003 7,0.050 0±0.002 9,0.071 2±0.003 0 and 0.084 4±0.004 3,respectively from PND1 to PND14 (P＜0.01).In the DEHP treated animals,when compared with the control group,IAR was significantly higher on PND14 (P＜0.05 or P＜0.01),while the total length density of all segments in unit area lung volume was significantly decreased (P＜0.05 or P＜0.01).Length density in medium-and high-dose subgroups were higher than that of low-dose subgroup by 0.082 9±0.001 8,0.077 2±0.002 0 and 0.071 3±0.003 7,respectively on PND14 (P＜0.05 or P＜0.01).Conclusions Medium-and high-dose DEHP affect the postnatal lung development in rats in a dose-dependent mode.

Phthalate exposure and childhood obesity

Phthalates are commonly used as plasticizers and vehicles for cosmetic ingredients. Phthalate metabolites have documented biochemical activity including activating peroxisome proliferator-activated receptor and antiandrogenic effects, which may contribute to the development of obesity. In vitro and in vivo studies suggest that phthalates have significant effects on the development of obesity, especially after prenatal exposure at low doses. Although few studies have examined the effects of phthalate on obesity development in humans, some work has shown that phthalates affect humans and animals similarly. In this paper, we review the possible mechanisms of phthalate-induced obesity, and discuss evidence supporting the role of phthalates in the development of obesity in humans.

Effects of di-( 2-ethylexyl ) phthalate on apoptosis of cytotrophoblasts in early pregnancy / 中华妇产科杂志

Objective To investigate the influence of di-(2-ethylexyl) phthalate (DEHP) on cell apoptosis and expression of Bcl-2 and bax in cultured human first trimester cytotrophoblasts. Methods Human first trimester cytotrophoblasts were cultured with DEHP at concentration of 0, 25, 50, 100 μmol/Lfor 24 hours. Cell apoptosis was detected by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) and flow cytometer method. The expression of apoptosis-associated genes, including Bcl-2 and bax, were detected by reverse transcription (RT)-PCR in cultured cytotrophoblast cells. The protein expression of Bcl-2 and bax in cytotrophoblast cells was measured by western blot. Results (1) The expression of Bcl-2: when incubated with DEHP at concentration of 0, 25,50 and 100 μmol/L, the expression of Bcl-2 were 1.00 ± 0.05, 1.03 ± 0.04, 1.04 ± 0.03, 1.04± 0.04,which did not show statistical difference ( P > 0.05 ). The expression of Bcl-2 protein were 0.11 ± 0.02,0.11 ±0.04, 0.12±0.02, 0.12 ±0.03, which also didn't reach statistical difference (P>0.05). (2)The expression of bax: when incubated with DEHP at concentration of 50 and 100 μmol/L, the expression of bax protein were 0.63 ± 0.04 and 0.81 ± 0.04, which were significantly higher than 0.23 ± 0.05 with DEHP at 0 μmol/L (P < 0.05). The expression of bax mRNA were 0.96 ± 0.04 and 1.02 ± 0.04, which was significantly higher than 0.81 ±0.05 with DEHP at 0 μmol/L (P < 0.05). (3) Apoptosis: when incubated with DEHP at concentration of 50 and 100 μmol/L for 24 hours, the apoptotic cell ratio were ( 18.8 ± 2.6) % and ( 20.3 ± 2.0) % by annexin V-FITC/PI staining, which were significantly higher than (10.6±1.4)% at 0 μmol/L and (18.1 ±4.6)% and (19.5 ±1.2)% by TUNEL staining, which were significantly higher than ( 11.2 ± 3.1 ) % at 0 μmol/L of DEHP (P < 0.05). Conclusion DEHP could induce apoptosis of cytotrophoblast cells by increasing bax gene expression, but had no effect on Bcl-2 expression.

Increase in hepatic ubiquinone on administration of diethylhexyl phthalate to the rat.

It is shown for the first time that the content of ubiquinone of liver increases (2·5 fold) on dietary administration of the widely-used industrial plasticizer diethylhexyl phthalate to the rat. The increase is localized almost entirely in mitochondria in which the concentration of the quinone per mg protein is 1·7 times the control. Incorporation of the radioactive precursor (acetate) reveals that the biosynthesis of ubiquinone is increased in the livers of plasticizer-administered animals. The rate of degradation is not altered.